Polyvinyl acetal resin sheets containing tetrahydrofurfuryl sucinate



Patented Dec. 26, 1939 UNITED STATES POLYVINYL ACETAL RESIN SHEETS CON- TAINING TETBAHYDROFURFURYL SUC- CINATE Henry B. Smith, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing.

Application October 5, 1938,

Serial No. 233,476

4 Claims." (01. 260-36) This invention relates to plastic compositions, and more particularly to compositions comprising a, polyvinyl acetal resin and a conditioning agent. One object of this invention is to pro- 5 duce compositions of matter which may be made into permanently transparent, strong and flexible sheets or films of desired thinness which are substantially waterproof, are unaffected by ordinary photographic fluids and possess the desired properties of a support for sensitive photographic coatings. Another object ofmy invention is to produce compositions of matter which can be made into sheets suitable for use in laminated, shatter-proof glass. Still another object is to produce compositions which can be rolled, ex-'- truded, molded or otherwise worked into relatively thick sheets and massive plastics. A further object is to produce compositions suitable for use in lacquers, artificial silk filaments, wrapping tissues and the like. Other objects will hereinafter appear.-

I have discovered that tetrahydrofurfuryl succinate is a very useful conditioning agent for polyvinyl acetal resins. .Not only does it serve as a plasticizer in the accepted sense of the term,

increasing the flexibility and toughness of polyvinyl acetal resin films, sheets, or other objects or masses containing it, but when. used in amounts of about 50 or 75 or more parts per 100 parts of certain of the polyvinyl acetal resins, namely the polyvinyl acetal resins in which a predominating proportion of the acetal groups are formaldehyde acetal groups or acetaldehyde acetal groups, it has an unusual and remarkable effect which-I may call elasticizing. That is to say, a sheet of polyvinyl formaldehyde or acetaldehyde acetal resin containing about or more parts of tetrahydrofurfuryl succinate per 100 parts of resin possesses the property which, in the rubber industry, is known as nerve: namely, the property of stretching to a considerable extent when tension is exerted upon it, and returning to its original dimensions when the tension is released. This property renders 500 or more parts of the solvent or solvent mix-' ture being used per 100.parts of the resin. From readily determined by experiment.

oAmong the polyvinyl acetal resins with which about 5 to 100 parts or more of tetrahydrofur- 'furyl succinate per 100 parts 'of resin may be employed, depending upon the nature of the resin and the purpose for which the sheets are to be used. Suitable proportions of tetrahydrofurfuryl 6 succinate for any resin and any purpose may be For the manufacture of sheets suitable for photographic film base, from 15 to 25 parts of tetrahydrofurfuryl succinate per 100 parts of resin are suit- 10 able. The resin solution is cast as a sheet, the solvent evaporated, and the sheet stripped from the casting surface.

Sheets for use in laminated glass may be formed by casting, or may be made without the 15 use of volatile solvent by extrusion, for example in the manner set forth in application Serial No. 147,934 of John S. Kimble and Ernest C. Blackard, filed June 12, 1937. For instance,

50 to or more parts of tetrahydrofurfuryl sucno cinate and parts of a polyvinyl acetaldehyde or formaldehyde acetal resin may be mixed in'a suitable, jacketed mixer at a lower temperature, for example 10 C., and the mixturemay then be worked on hot rolls, in the manner described in a United States Patent 2,048,686 of F. R. Conklin, until complete homogenization has taken place. The mass thus produced may then be extruded through an annular die, and the tube so formed slit to form a sheet. When the resin used is a polyvinyl formaldehyde acetal resin, it will usually be found necessary to use '75 or more parts of tetrahyd ofurfuryl succinate per 100 parts of resin.

The polyvinyl acetal resins can be prepared by reacting polyvinyl alcohol with an aldehyde in the presence of an acetal condensation catalyst,v e. g., a mineral acid. These resins can also be prepared by simultaneously de-esterifying a polyvinyl aliphatic ester and reacting the de-esterification product with an aldehyde in the presence of a de-esterifying catalyst and acetal condensation catalyst. Mineral acids are catalysts for bothde-esterification and acetal formation.

tetrahydrofurfuryl succinate is useful may be mentioned, as illustrative examples, the polyvinyl formaldehyde acetal resins, the polyvinyl acetaldehyde acetal resins, the polyvinyl formaldehyde acetaldehyde mixed acetal resins, the 50 polyvinyl butyraldehyde acetal resins, and the polyvinyl butyraldehyde acetaldehyde mixed I acetal resins.

Examples of the preparation of polyvinyl formaldehyde acetal resins may be found in r United States Patent 1,955,068, Examples 1, 4 and 5; in United States Patent 2,036,092, Examples 1, 2, 3, 7 and 8; in British Patent 454,691, Examples 1, 2, 3, 4, ,5, 6 and 7; in British Patent 404,279, Example 3; and in British Patent 436,072, Examples 1, 2, 3, 4, 5, 6, and 7. Further examples of the preparation of polyvinyl formaldehyde acetal resins are as follows:

25 lbs. of polyvinyl acetate, the viscosity of whose molar solution (86.08 'g. per liter) in benzene was 45 centipoises, was dissolved in 75 lbs. of 70% acetic acid. To this solution were added 56 grams of hydroxylamine hydrochloride,

for stabilizing the resin, 5.25 lbs. of trioxymethylene, and 6.25 lbs. of 35% HCl. The reaction mixture was allowed to stand for 5 days at 40 C., after which it was diluted with acetic acid. The

resin was precipitated by pouring into cold water,

washed, and dried. Analysis showed the resin to have an acetate group content equivalent to 10.6% by weight of polyvinyl acetate and a hydroxyl group content equivalent to 7.1% by weight of polyvinyl alcohol. The stabilization of polyvinyl acetal resins by hydroxylamine is claimed in the application of Joseph B. Hale, Se rial No. 149,916, filed June 23, 1937, Patent No. 2,146,735.

70 lbs. of polyvinyl acetate, the viscosity of whose molar solution in benzene was 45 centipoises, was dissolved in a mixture of 336 lbs. of glacial acetic acid and 224 lbs. of water. After solution was effected, there were added a solution of 318 grams of sodium nitrite in 500 cc. of water, for stabilizing the resin, 15.2 lbs. of trioxymethylene and 17.5 lbs. of 35% HCl. The reaction mixture was allowed to stand for 5 days at 40 C., whereupon 5 lbs. additional 35% HCl was added and the reaction continued for 6 days longer: a total of 11 days at 40 C. The reaction mixture was then diluted with a mixture of acetic acid and ethyl alcohol, and the resin was precipitated by pouring into cold water, washed, and dried. Analysis showed the resin to have an acetate group content equivalent to 10.7% by weight of polyvinyl acetate and a hydroxyl group content equivalent to 11.2% by weight of polyvinyl alcohol. The stabilization of polyvinyl acetal resins by nitrous acid is claimed in the application of Charles R. Fordyce and Martti Salo, Serial No. 159,193, filed August 14, 1937, Patent No. 2,159,263.

Examples of the preparation of polyvinyl acetaldehyde acetal resins may be found in United States Patent 44,730, Example 1; United States Patent 1,955,068, Example 2; United States Patent 2,036,092, Examples 4, 5 and 6; British Patent 466,598, Examples 1, 2, 3, 4 and 7; British Patent 404,279, Examples 1, 2, 4, 5, 6, 7 and 8; United States Patent 1,990,399; and French Patent 808,578, Examples 1, 2 and 3.

Additional examples of the preparation of polyvinyl acetaldehyde acetal resins are as follows:

100 lbs. of polyvinyl acetate, the viscosity of whose molar solution in benzene was 45 centipoises, was dissolved-in 300 lbs. of 95% ethyl alcohol. To this solution were added 30 lbs. of paraldehyde and 25 lbs. of 35% H0]. The reaction mixture was allowed to stand for 4 da ys at 40 C., after which it was diluted with ethyl alcohol, and the resin precipitated by pouring into cold water, washed and dried. Analysis showed the resin to have an acetate group content equivalent to 2.1% by weight of polyvinyl acetate and a hydroxyl group content equivalent to 12.9% by weight of polyvinyl alcohol.

25 lbs. of polyvinyl acetate, the viscosity of whose molar solution in benzene was 45 centipoises, was dissolved in 75 lbs. of 95% ethyl alco: hol. To this solution was added 8 lbs. of paraldehyde and a solution of 3 lbs. 12 ozs. of sulfuric acid in 3 lbs. 12 ozs. of 95% ethyl alcohol. The reaction mixture was allowed to stand for 7 days at 40 C., after which it was diluted with ethyl alcohol, and the resin precipitated by pouring into cold water, washed, and dried. Analysis showed the resin to have an acetate group content equivalent to 1.7% by weight of polyvinyl acetate and a hydroxyl group content equivalent to 13.8% by weight of polyvinyl alcohol.

50 lbs. of polyvinyl acetate, the viscosity of whose molar solution in benzene was 45 centipoises, was dissolved in a mixture composed of 50 lbs. of 95% ethyl alcohol and 90 lbs. of ethyl acetate. To this solution was added 19.2 lbs. of paraldehyde. Then a catalyst consisting of 5 lbs. of 95% sulfuric acid diluted with 5 lbs. of water was added. After thorough mixing, the reaction was allowed to proceed at 40 C. for 8 days. The reaction mixture was then diluted with acetone, and the resin precipitated by pouring into cold water, washed and dried. Analysis showed the resin to have an acetate group content equivalent to 3.3% of polyvinyl acetate and a hydroxyl group content equivalent to 6.5% of polyvinyl alcohol.

Examples of the preparation of polyvinyl formaldehyde acetaldehyde mixed acetal resins may be found in British Patent 430,136, Examples 1, 2, 3, 4, 5 and 6; British Patent 445,565, Example 2; British Patent 465,873, Examples 1, 2, 3, 4, 5 and 6; French Patent 808,586, Examples 1, 2, 3, 4, 5, 6, 12, 13, 14, 15, 16, 17, 18 and 19.

Additional examples of the preparation of polyvinyl formaldehyde acetaldehyde mixed acetal resins are given to the application of Ralph H. Talbot, Serial No. 85,960, filed June 8, 1936, as follows:

Example 1 100 parts (1.16 mol. calculated as monomeric vinyl acetate) of a polyvinyl acetate (45 centipoises), 100 parts of ethyl alcohol, 180 parts of ethyl acetate, 34 parts (.77 mol. as monomeric acetaldehyde) of paracetaldehyde and 5.8 parts (.196 mol. as monomeric formaldehyde) of paraformaldehyde were placed in an enamelled vessel and brought into solution by stirring. When solution was complete, 10. parts of sulfuric acid (sp. g. 1.84) in parts of water were added, and the mixture stirred. The mixture was maintained at a temperature of 40 C. for 144 hours. The contents of the vessel were then diluted with about two and a half volumes of acetone, and the mixture precipitated into water. The precipitated resin was washed free from impurities by repeated changes of cold water, and dried. The resin, when analyzed, gave a hydroxyl group content equivalent to about 6.4 per cent by acetal andabout 80.3 per cent by moles of polyvinyl acetaldehyde acetal. The resin was soluble in acetone to an extent which permitted coatin a film or sheet from the resin.

"Example 2 50 parts (.58 moi. as monomer) of polyvinyl acetate (45 centipoises), 50 parts of ethyl alcohol, 90 parts of ethyl acetate, 17 parts (.385 mol. as monomer) of paracetaldehyde; 2.9 parts (.098 mol. as monomer) of paraformaldehyde, 5 parts of sulfuric acid and 5 parts of water were treated as in Example 1 for 161 hours. The well washed and dried resin gave upon analysis a. hydroxyl group content equivalent to about 9.6% by weight of polyvinyl alcohol, an acetate group content equivalent to about 4.1% by weight of polyvinyl acetate, 9. formaldehyde acetal group content equivalent to about 13.9 per cent by weight of polyvinyl formaldehyde acetal, and an acetaldehyde acetal group con.- tent equivalent to about 69.9 per cent of polyvinyl acetaldehyde acetal. The polyvinyl acetal portion of the resin was therefore made up of about 18.5 percent by moles of polyvinyl formaldehyde acetal and 81.5 per cent by moles of polyvinyl acetaldehyde acetal. The resin was soluble in acetone to an extent which permitted coating a film or sheet from the resin.

' "Example 3 1300 parts (15.1.mol. as monomer) of a polyvinyl acetate (45 centipoises) 1700 parts of ethyl acetate, 2250 parts of ethyl alcohol (95%) and 48 parts. (1.57 mol. as monomer) of paraformaldehyde (trioxymethylene) were placed in a vessel equipped with a reflux condenser and a means of agitation, and the contents brought to a temperature of about C. by means of steam heating. 182.25 parts of sulfuric acid (sp. g. 1.84) dissolved in 51.5 parts of water were added, and the whole was heated at about 70 C. for about five hours, agitating throughout. At this point, 266.4 parts (6.05 mol. as monomer) of paracetaldehyde were added and heating at about 70 C. with agitation was continued for a further period of twenty hours. The contents of the reaction vessel were neutralized with ammonium hydroxide and diluted with water precipitating the resin as a cake. The cake was cut into small pieces and repeatedly washed with hot water until the resin was freefrom solvents, salts and other impurities. lhe resin, upon analysis, showed a hydroxyl group content equivalent to about 10.1 per cent by weight of polyvinyl alcohol, an acetate group content equivalent to about 3.2 per cent by weight of polyvinyl acetate, the remainder of the weight of the resin being polyvinyl acetal. The polyvinyl acetal portion of the resin was made up of about per cent by moles of polyvinyl acetaldehyde acetal and about 20 per cent by moles of polyvinyl formaldehyde acetal. The resin was not quite soluble in'acetone, but could be made to dissolve by admixing small amounts of other solvents, such as alcohols, with the acetone.

Examples of the preparationv of polyvinyl butyraldehyde acetal resins may be found in United States Patent 2,044,730, Examples 2, 5 and 6; British Patent 466,598, Example 5; French Patent 813,303, Example 1; French Patent 813,514, Examples 1, 2, 3 and 4; and British Patent 459,879, Examples 1, 2, 5, 6, 7, 8, 9 and 10.

An additional example ,of the preparation of a polyvinyl butyraldehyde acetal resin is as follows:

20 lbs. of polyvinyl acetate, the viscosity of whose molar solution in benzene was 45 centipoises, was dissolved in 20 lbs. of ethyl alcohol and 36 lbs. of ethyl acetate. To this solution was added 13 lbs. of butyraldehyde anda solution-of 2 lbs. of sulfuric acid in 2 lbs. of water. The reaction mixture was allowed to stand for 8 days at 40 C., after which it was diluted with acetone, and theresin precipitated by pouring into cold water, washed and dried. Analysis showed the resin to have an acetate group content equivalent to 7.8% by weight of polyvinyl acetate and a hydroxyl group content equivalent to 4.8% by weight of polyvinyl alcohol.

An example of the preparation of a polyvinyl butyraldehyde acetaldehyde mixed acetal resin is given in French Patent 813,303, Example 2.

What I claim as my invention and desire to be secured by Letters Patent of the United States 1. A transparent, rubbery sheet comprising parts of a polyvinyl acetal resin in which apredominating proportion of the acetal groups are selected from the group consisting of formaldehyde acetal groups and acetaldehyde acetal groups, and at least 50 parts, approximately, of tetrahydrofurfuryl succinate as an elasticizer therefor.

2. A transparent, rubbery sheet comprising 100 parts of a polyvinyl acetaldehyde acetal resin and at least 50 parts, approximately, of tetrahydrofurfuryl succinate as an elasticizer therefor.

3. A transparent, rubbery sheet comprising 100 parts of a polyvinyl formaldehyde acetal resin and at least 60 parts, approximately, of tetrahydrofurfuryl succinate as an elasticizer therefor.

4. A transparent, rubbery sheet comprising a polyvinyl acetal resin in which a predominating proportion of the acetal groups are selected from the group consisting of formaldehyde acetal groups and acetaldehyde acetyl. groups, and an amount of tetrahydrofurfuryl succinate sufficient to impart to the sheet a rubbery character without substantially impairing its transparency.

HENRY B. SMITH.

Patent No.. 2,l8h,hl;.5.'

CERTIFICATE OF CORRECTION.

December 26, 1 9 59,.

HENRY B. SMITH.

It is hereby certified that error appears in the printedspecificationof the above numbered patent requiring correctionas follows: Page 3, see

ond column, line '57, claim 1;, for "acetyl" read acetal; and that the said Letters Patent should be read withthis correction therein that the same ney conform to the record ,of the case in the Patent Office.

Signed and sealed this 2nd day of April, A. D. 1 m.

Henry Van Aredale,

(Seal) Acting Commissioner of Patents. 

